[PLOT OPTIONS]

[PlotCurve options]

	Note that all these options only take effect for the 
	next plot.

	<Single phase> plots the lightcurve for one full 
	orbit.
	<Double phase> plots the lightcurve for two 
	consecutive orbits.
	<Zoom Eclipse (P)> and <Zoom Eclipse (S)> will zoom on 
	the eclipse of the primary or secondary, respectively.
	If observational data for the chosen <filter> 
	(see next) are in memory, they will be overplotted.

	<Filters>: Nightfall computes the lightcurve for several 
	different <filters> commonly used in astronomy. 
	Each of these filters is only sensitive for a 
	certain range of wavelenghts (just like the human 
	eye as well).
	Options include the UBVRIJHK broadband filters, 
	which range from the ultraviolet (U) to the 
	infrared (JHK), and the narrow-band Stroemgren uvby
	filters. The sensitivity of the <human eye> is best 
	matched by the <V> and the <Stroemgren v> filters. 

[ViewGeometry options]

	These options include visualization of the 
	Roche potential (actually a cross-section in the 
	orbital plane), and visualization of the stars 
	themselves (or the surface grid defining them).

	In the Roche <Potential Contours> 
	plot, contours are plotted for the stars, the Roche 
	lobes, and the Lagrange 2 potential, which limits
	overcontact systems.

[StarView and RocheSlicer] 

	are interactive viewing facilities; no options to set.
  
[Postscript]

	If toggled, output from <PlotCurve> or <ViewGeometry>
	will go to a postscript file named <Nightfall.ps>.
	This file will be <overwritten> by the next plot.
 
[OpenGL]

	If Nightfall has been compiled with OpenGL support,
	you can toggle between OpenGL animation and 
	gnuplot/pgplot animation. In OpenGL mode you can drag
	with the left mouse button to change the <viewpoint>, and
	with the middle  mouse button to <zoom>. To <reset>, use the
	space bar. 

	With <File/Save animation> you
	can save the individual frames of the animation 
	as JPEG files to generate an MPEG <movie>.

	With <Edit/Preferences> you can switch between wireframe, 
	points, and solid display. You can also switch on/off
	textures, and switch on/off the display of labels and axes.

	The following keybindings are available in the OpenGL window:

	<right arrow> zoom out
	<left arrow>  zoom in
	<space>	      reset to real observer viewpoint
	<f>     switch to 'points' display mode
	<l>     switch to 'wireframe' display mode
	<o>     switch to 'opaque' display mode
	<t>     toggle textures on/off
	<w>     cycle through texture type
	        (image/temperature/gravity/flux/velocity)
	<p>     toggle primary texture on/off
	<s>     toggle secondary texture on/off
	<a>     toggle axes on/off
	<m>     toggle movie mode on/off